1. Technical Field
The present invention relates to a mechanically regulated time indicator particularly suited for use in wrist-watches.
2. Related Art
The present invention falls into the family of so-called tourbillon time indicators. The conventional type of such a time indicator is represented by the Bréguet Tourbillon from 1795. In this device, a balance, its spiral spring and its escapement are assembled in the interior of a turning cage, the rotational speed of which is one revolution per 60 seconds. The cage turns about a double bearing gear.
In the development of wristwatches, a reduction in the number of bearings is observed. The patent GB-21421 from 1892 describes a tourbillon cantilevered in a single large bearing. Patent CH-353679 from 1961 describes a cantilevered bearing construction of the ball bearing type wherein the ball bearing replaces the thick smooth bearing used up to that time. Nowadays, cantilevered bearings of the ball bearing type are widely used, exemplified by the constructions in accordance with U.S. Pat. No. 4,132,061 from 1977.
The speed of rotation can be less than 60 sec. per revolution as is shown by the tourbillon of Albert H. Potter published in the work “Horlogerie Ancienne” no. 22, 2nd semester 1987, pages 64-71.
Since then, numerous variations in construction have been reported. The work “Das Tourbillon” by Reinhard Meis, Callway Verlag Münich, 2nd Ed., 1993, provides a very good overview of the subject. Thus, one can differentiate tourbillons mounted in a non-visible or a visible fashion, as seen from the side of the dial. To be non-visible, a tourbillon is mounted with its base on the dial side. To be visible, a tourbillon is mounted with a bridge on the dial side.
Often, the tourbillons are arranged in the six o'clock, twelve o'clock positions on the dial or in the middle of the dial. Such creations of tourbillons arranged in the six o'clock or twelve o'clock positions are shown in the work “Das Tourbillon” by Reinhard Meis, Callway Verlag Munich, 2nd Ed., 1993. The creation in the middle of the dial implies that the tourbillon is mounted on the central staff of the time indicator, resulting in a relatively thick construction.
A particularly aesthetic tourbillon is known by the name flying tourbillon. Such a flying tourbillon is described, for example, in the work “Drehganguhren” by Alfred Helwig, Verlag der Deutschen Uhrmacher-Zeitung, Berlin, 1927. This flying tourbillon has no component that covers the cage. Another flying tourbillon, visible from the dial side and projecting beyond the movement is reported in the work “Faszination der Uhrentechnik” by Reinhard Meis, page 276, Laterna magica.
All these tourbillon constructions are known to present the disadvantage of being understood as components, which are indissociable from the watch movement. This makes their final adjustment tricky and their customisation (decoration, design, frequency) if not impossible, then certainly difficult.
An object of the present invention is to provide an astute construction of a time indicator of the balance spring flying tourbillon type visible from the dial side. A further object of the invention is to provide a solution to the above-mentioned disadvantage and to describe an economical and flexible process for the assembly and/or adjustment of watches. A final object of the invention is to provide a particularly aesthetic and slim time indicator for wristwatches.
The object is provided by the invention as defined by the Claims.
The present invention relates to a time indicator of the balance spring flying tourbillon type. This flying tourbillon is visible from the dial side and comprises a balance bridge forming a cage with a collet. Its cantilevered single bearing supports the said flying tourbillon assembly. The cantilevered single bearing is of the ball bearing type. The flying tourbillon assembly is designed as an independent tourbillon module, visible from the dial side of the movement and separable from the other side of the movement. All the components can be assembled together and adjusted independently from the movement.